Apparatus for transforming sound into electrical energy



March 4, 1930. H. c. HAYES 1,749,285

APPARATUS FOR TRANSFORMING SOUND INTO ELECTRICAL ENERGY Original-Filed June 30, 1924 IN V EN TOR. flan e 6'. l/qes I ATTORNEYS.

Patented Mar. 4, 1930 UNITED STATES PATENT OFFICE APPARATUS FOR TRANSFORMING SOUND INTO ELECTRICAL ENERGY Original application filed June 30, 19%, Serial No. 723,427. Divided and this application filed November 11, 1927. Serial No. 232,702.

(GRANTED UNDER THE ACT OF MARCH 3, 1883, AS AMENDED APRIL 30, 1928; 370 0. G. 757) My invention relates broadly to all types of ap aratus which has for its function the transfbrmation of the energy of sonic undulations in a fluid into electrical energy and more particularly to microphones.

This application is a divisional applicatlon of the subject matter contained in m original application Serial No. 723,427, ed 30 June 1924, issued as Patent No. 1,729,383,

Sept. 24, 1929, having similar objects, which enumerated are as follows:

The primary object ofmy invention is to produce a microphone in which there is no impingement of the sonic undulations upon a diaphragm, but one in which the diaphragm will move with the movement of the fluid about it.

This object employs the utilization of the viscosity of the fluid in which the diaphragm is mounted and this serves a useful purpose in the production of a micro bone which will more faithfully transform t e energy of the sonic undulations into electrical ener than those types of micro bones in WhlCh the sound waves vibrate t e diaphragm by impinging directly thereon.

In the use of the apparatus as disclosed in the parent application and in a copending,

application Serial Number 232,701, filed Nov.

11, 1927, I have found that there are certain uses to which my improved microphone may be adapted in which a highly resonant diaphragm may be employed with added advantages. It is therefore, a further object of this application to produce a microphone which may be highly resonant to a sonic V1- bration of a particular frequency or to a plurality of them of different frequencies.

My invention consists substantially in the construction combination and arrangement of parts associated therewith or as will be more fully hereinafter set forth as shown by the accompanying drawings and finally pointed out in the appended claims.

Of the drawings, Figure 1 is a longitudinal section through the apparatus, Figure 2 is a transverse section throu h the magnetic gap of the device, while Figure 3 is a view similar to Figure 2 but showing the use of 50 crinkled filaments.

Referring to Fig. 1 of the drawing which represents a sectional view of my improved microphone the letters N and S refer to the north and south poles of one magnet the poles of which are brought into close proximity to each other or the north or south poles of two magnets placed end to end. As the substitution of one magnet for two or vice versa makes no difference in the operation of the device I will describe it as consisting of two magnets placed end to end in the manner shown.

One of the magnets 5 is hollow as shown at 6 or if one magnet is used the hollow portion of the pole upon the other side of the magnetic gap is filled with material 7 so that the S pole presents a flat surface to the sonic vibrations passing through the hollow portion 6. Upon one end of the magnet 5 I have provided a mouthpiece 3 for the direction of speech or other sounds within the hollow portion 6 of the magnet '5 which in turn conducts the vibrations to the magnetic gurrounding the magnetic gap I have provided a dust cap 9 which serves a multiplicity of functons, one of which is the production of a chamber 4 surrounding the magnetic gap, and others of which are to prevent dust from accumulating within the magnetic gap, serving as a means for mounting a diaphragm Within the magnetic gap and the preventing of movements of the air surrounding the microphone from reaching the diaphragm.

Within the magnetic gap I have mounted a plurality of elements 8 which I have chosen to call diaphragms for want of a better term. These diaphragms consist of a filament or ribbon-like wire of a fineness similar to that of the fine threads of glass that are to be found floating in the air in a glass blowing establishment. The mass of such a filament is so small in comparison to its area that the viscosity of the air is sutficient to carry the filament with it in its movements without any appreciable relative change between the filament and the surrounding air..

I have found that not only will a filament of this size follow the air in its larger movements but also it will be carried with it in its 100 smaller movements such as the compressions and rarefactlons 1n the atmosphere WhlCll are generally termed sonic vibrations.

In general use I have found that the'filament should be untensioned to follow the broad range of sounds entering the mouth-' piece 3. However, as in sonic depth finding, where a sonic signal of one tone is utilized, I have found that a highly resonant diaphragm is more responsive to weak signals than the non-resonant type. To enable each filament to be tuned to resonance with a particular wave I have provided the filament with a mounting 10 upon the outer end of which is an electrical terminal 11. At the other end of the filament I have provided a tension means which consists of a threaded sleeve 12 mounted in the casing 9 by means of threaded elements 15. Within the sleeve 12 is threaded a tension element 14 to which the filament 8 is attached. About the sleeve 12 is a fastening element 13 which constitutes the other terminal of the filament 8. Similarly in this case as in the others referred to the filament may be crinkled as is illus-' trated in Fig. 3 to increase the eifect of the viscosity of the fluid upon the filament.

When the tension is placed upon the filament 8 it may be made highly resonant to a sonic vibration of a particular frequency or where a plurality of filaments are used each may be tuned to the same frequency or to a plurality of various definite frequencies;

It will be understood that the above description and accompanying drawing comprehend only the general and preferred embodiment of my invention and that minor detail changes in the construction and arrangement of parts may be made within the scope of the appended claims without sacrificing any of the advantages of my invention.

The invention herein described may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon or therefor.

Having thus described my invention, what I claim is as follows:

1. An apparatus for transforming sound into electrical energy, comprising a sound directing means, a magnet having pole pieces, one of said pole pieces being hollow and in sonic communication with said U directing means, a magnetic gap between said pole pieces, a filamentary conductor suspended within said magnetic gap and adapted to receive directly the impulses from said sound directing means and means for exerting a tension upon said filamentary conductor.

2: In an apparatus of the character .described, the combination of a magnet having a plurality of poles, a magnetic gap between the poles, means for directing sonic vibrations within the magnetic gap, a filamentary conductor disposed within the magnetic gap and adapted to receive directly the im ulses from said directing means and means or exerting a tension upon said conductor, said means being disposed in longitudinal alignment with said conductor. Y

3. In an apparatus of the character described, the combination of a plurality of magnetic poles, a magnetic gap between said poles, means for directing sonic vibrations Within the magnetic gap, an element surrounding said gap and forming a chamber thereabout, a filamentary conductor mounted within said gap and supported by said element, said conductor being adapted to receive directly the impulses from said directing means and means mounted upon said element for exerting a tension upon said filav ment.

4. In anapparatus of the character described, the combination of a magnet having a plurality of poles, a magnetic gap between the poles, means for directing sonic vibrations within the magnetic gap, a plurality of filamentary conductors disposed within the magnetic gap and adapted to receive directly the impulses from said directing means and means for exerting a tension upon each of said conductors, said means being disposed in longitudinal alignment with said conductors.

5. In an apparatus of the character described, the combination of a plurality of magnetic poles, a magnetic gap between said poles, means for directing sonic vibrations within the magnetic gap, an element surrounding said gap and forming a chamber thereabout, a plurality of filamentary conductors mounted within said gap and supported by said element, said conductors being adapted to receive directly the impulses from said directing means and means mounted upon said element for exerting a tension upon each of said conductors. 1

6. An apparatus for transforming sound into electrical energy comprising a sound concentrating means, a magnet having pole pieces, one of said pole pieces being hollow, a magnetic gap between said pole pieces, a

crinkled filamentary conductor suspended within said magnetic gap and means for exerting a tension upon said filamentary conductor.

7. In an apparatus of the character described, the combination of a magnet having a plurality of poles, a magnetic gap between the poles, means for directing some vibrations within the magnetic gap, a crinkled filamentary conductor disposed within the magnetic gap and means for exertinga tension upon said conductor, said means disposed in longitudmal alignment with said conductor.

8 In an apparatus of the character described, the combination of a magnet hav- 1ng a plurality of poles, a magnetic gap between sald poles, means for directing sonic vlbrations within the magnetic gap, an elemeans and means for exerting a tension upon each of said conductors, said means disposed in longitudinal alignment with said conductors.

10. In an apparatus of the character described, the combination of a magnet having a plurality of poles, a magnetic gap between said poles, means for directing sonic vibrations within the magnetic gap, an element surrounding said gap and forming a chamber 0 thereabout, a plurality of crinkled filamentary conductors mounted within said gap and supported by said element, and means upon said element for exerting a tension upon each of said conductors.

HARVEY O. HAYES. 

